Fluids based on fluorocarbon compounds are widely used in systems for the transfer of heat by compression of vapor, in particular air conditioning, heat pump, refrigeration or freezing devices. These devices have it in common that they are based on a thermodynamic cycle comprising the vaporization of the fluid at low pressure (in which the fluid absorbs heat); the compression of the vaporized fluid up to a high pressure; the condensation of the vaporized fluid to give a liquid at high pressure (in which the fluid discharges heat); and the reduction in pressure of the fluid in order to complete the cycle.
The choice of a heat-transfer fluid (which can be a pure compound or a mixture of compounds) is dictated, on the one hand, by the thermodynamic properties of the fluid and, on the other hand, by additional constraints. Thus, a particularly important criterion is that of the impact of the fluid under consideration on the environment. In particular, chlorinated compounds (chlorofluorocarbons and hydrochlorofluorocarbons) exhibit the disadvantage of damaging the ozone layer. Thus, nonchlorinated compounds, such as hydrofluorocarbons, fluoroethers and fluoroolefins, are from now on generally preferred to them.
It is also still necessary to develop other heat-transfer fluids exhibiting a lower global warming potential (GWP) than that of the heat-transfer fluids currently used and exhibiting equivalent or improved performances.
The document U.S. Pat. No. 5,076,064 describes the replacement of trichlorofluoromethane (CFC-11) par other refrigerants in centrifugal compressors. The use of 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123) is in particular provided in this document. However, it remains desirable to use refrigerants which are even less toxic to the ozone layer and which exhibit a lower GWP than HCFC-123.
The document WO 2010/141669 describes the use of cis-1,1,1,4,4,4-hexafluorobut-2-ene (or Z-HFO-1336mzz) as refrigerant, in particular as a replacement for CFC-11 and HCFC-123. However, the performance of this compound is unsatisfactory. In particular, its volumetric capacity is markedly lower than that of HCFC-123.
The document WO 2010/141527 describes azeotropic or quasi-azeotropic compositions comprising Z-HFO-1336mzz and another compound which can be ethanol, 2-chloro-3,3,3-trifluoropropene, methanol, trans-1,1,1,4,4,5,5,5-octafluoropent-2-ene, 2-bromo-3,3,3-trifluoropropene, methyl acetate, acetone, chloroform, n-hexane or 1-chloro-3,3,3-trifluoropropene. These mixtures are highly inflammable and/or are not suitable for the replacement of refrigerants such as HCFC-123.
The document WO 2010/100254 describes in a general way the use of mixtures of fluoroolefins of HFO-1354 and HFO-1336 type. The HFO-1354 can be 2,4,4,4-tetrafluorobut-1-ene and HFO-1336 can be HFO-1336mzz. However, the isomeric form of the latter compound is not specified.
There still exists a need to develop other heat-transfer fluids which are less toxic to the ozone layer and which exhibit a relatively low GWP, in order to replace the ordinary heat-transfer fluids.
In particular, it is desirable to develop heat-transfer fluids having a low GWP which can replace HCFC-123 while offering similar, indeed improved, energy performances, it being possible for the replacement preferably to be carried out without modifying the existing installations or their operating parameters.